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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2022 Intel Corporation. All rights reserved. */
#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "cxlmem.h"
#include "cxlpci.h"
* DOC: cxl port
* The port driver enumerates dport via PCI and scans for HDM
* (Host-managed-Device-Memory) decoder resources via the
* @component_reg_phys value passed in by the agent that registered the
* port. All descendant ports of a CXL root port (described by platform
* firmware) are managed in this drivers context. Each driver instance
* is responsible for tearing down the driver context of immediate
* descendant ports. The locking for this is validated by
* The primary service this driver provides is presenting APIs to other
* drivers to utilize the decoders, and indicating to userspace (via bind
* status) the connectivity of the CXL.mem protocol throughout the
* PCIe topology.
static void schedule_detach(void *cxlmd)
static int cxl_port_probe(struct device *dev)
struct cxl_port *port = to_cxl_port(dev);
struct cxl_hdm *cxlhdm;
int rc;
if (!is_cxl_endpoint(port)) {
rc = devm_cxl_port_enumerate_dports(port);
if (rc < 0)
return rc;
if (rc == 1)
return devm_cxl_add_passthrough_decoder(port);
cxlhdm = devm_cxl_setup_hdm(port);
if (IS_ERR(cxlhdm))
return PTR_ERR(cxlhdm);
if (is_cxl_endpoint(port)) {
struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport);
struct cxl_dev_state *cxlds = cxlmd->cxlds;
rc = devm_add_action_or_reset(dev, schedule_detach, cxlmd);
if (rc)
return rc;
rc = cxl_hdm_decode_init(cxlds, cxlhdm);
if (rc)
return rc;
rc = cxl_await_media_ready(cxlds);
if (rc) {
dev_err(dev, "Media not active (%d)\n", rc);
return rc;
rc = devm_cxl_enumerate_decoders(cxlhdm);
if (rc) {
dev_err(dev, "Couldn't enumerate decoders (%d)\n", rc);
return rc;
return 0;
static struct cxl_driver cxl_port_driver = {
.name = "cxl_port",
.probe = cxl_port_probe,